Patent document 1 discloses a technology in which the disclosed invention is applied to an engine. In this engine, a switching between a first driving system (for example, a homogenous combustion) at a high-revolution-and-high-load side and a second driving system (for example, a stratified combustion) at a low-revolution-and-low-load side which has a higher fuel efficiency than the first driving system is carried out. When a driving region of the engine is switched from a second driving region in which the second driving system is carried out to a first driving region in which the first driving system is carried out, a depression reaction force (pedal effort) of an accelerator pedal is abruptly increased by a predetermined pedal effort increment, at a stage at which the driving region of the engine enters a boundary driving region immediately before the driving region of the engine is switched to the first driving region.
In addition, this pedal effort increment is released when the driving region is returned from the boundary driving region to the second driving region.